statistics

posted by Sandra

Can you please tell me how to solve for the following?

Pedro took an exam in a class in which the mean was 64 with a standard deviation of 6. If his z score was +3, what was his exam score?

A students commute to school is normally distributed with a mean of 31 min and a standard deviation of 7 min. What is the probability that the student gets to school in 17 to 31 min?

Are the formulas the same for these?

And last one I need help with this:

Assume a normally distributed set of test scores with a mean of 100 and a standard deviation of 20. Find the probability that a person selected at random will have a score of the following:

a-between 60 and 140
b-less than 60

THANK YOU! I just need to know how to solve please.

  1. PsyDAG

    Equations are the same.

    Z = (score-mean)/SD

    For the second one, find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z scores.

    For the last problem, use the same equation and table.

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